The invention relates to an inclination gauge comprising a reservoir containing a clear liquid and a gas bubble and light emitting and light detecting means arranged at opposed positions with regard to said reservoir. It is intended to convert the movement of the gas bubble in the reservoir to an electric signal. By this it is no longer necessary to monitor directly the gas bubble in the reservoir. Also it is possible to provide self-adjusting devices.
From U.S. Pat. No. 4,625,423 it is known to direct a beam of light through a tubular reservoir containing either liquid or a gas volume. When light is transmitted through the liquid a converging effect is obtained. When light traverses to the gas volume a non converging beam leaving the reservoir is realized. By monitoring the change in light intensity at the spot of the light dependent resistance, information can be obtained with regard to the position of the gas volume in the reservoir. However, the transition from converging to parallel and diverging is a continuous process. This means that only by considerable amplification of the light dependent resistance can an exact prediction be obtained about the position of the inclination gauge. However, if there are slight changes in the light emitting source and/or the transparency of the reservoir and/or its contents, the results of the measurements will be affected. This means that this device is not reliable in long term.